Gas, e.g., exhaust gas, treatment devices such as catalytic converters, evaporative emissions devices, hydrocarbon scrubbing devices, diesel particulate traps, non-thermal plasma reactors, and the like, are employed in various applications to physically and/or catalytically treat environmentally unfriendly gas emissions. Such gas treatment devices incorporate a substrate, support, monolith, or brick, which includes a catalyst material coated thereon. A mounting device such as a mat support material comprising an intumescent material, non-intumescent material, or a combination of both, is disposed about the substrate forming a mat support material/substrate subassembly.
In order to meet the stringent requirements imposed by regulations governing the emission of pollutants, gas treatment devices are designed such that they can withstand higher temperatures over longer periods, e.g., so that they can be disposed in a close coupled (e.g., about 12 inches from the manifold) or manifold location where temperatures reach and exceed about 1,200° C. The catalysts of these gas treatment devices often degrade and their catalytic performance is reduced at temperatures greater than 1,000° C. Of the possible causes for this degradation in performance, sintering of the support upon which the catalyst is deposited, and sintering of the catalyst's active phase and/or encapsulation thereof by the support are among those most frequently blamed.